Surface cooler

ABSTRACT

A surface cooler for interposing in ram air or the like. Aerodynamic devices at the leading end of the cooler capture high energy air from the free air stream outwardly of the cooler mounting surface and divert the more stagnant air at the mounting surface away from the cooler inlet, the function being to reject heat to this captured air from a fluid used as a coolant in a location remote from the cooler. At the trailing end of the cooler other aerodynamic devices utilize the air flowing over the cooler to facilitate venting of a system fluid.

United States Patent [191 Simmons et al.

[ SURFACE COOLER [75] Inventors: Carl E. Simmons; Joseph F.

Fernandes, both of Dayton, Ohio [73] Assignee: United Aircraft Products, Inc.,

Dayton, Ohio [22] Filed: May 30, 1972 [21] Appl. No.: 258,127

7/1949 Mull 62/241 1,412,073 4/ 1922 Wagerseil 244/7 Primary Examiner-Charles J. Myhre Assistant Examiner-Theophil W. Streule, Jr. AttorneyJ. E. Beringer et al.

[57] ABSTRACT A surface cooler for interposing in ram air or the like. Aerodynamic devices at the leading end of the cooler capture high energy air from the free air stream outwardly of the cooler mounting surface and divert the more stagnant air at the mounting surface away from the cooler inlet, the function being to reject heat to this captured air from a fluid used as a coolant in a location remote from the cooler. At the trailing end of the cooler other aerodynamic devices utilize the air flowing over the cooler to facilitate venting of a system fluid.

12 Claims, 7 Drawing Figures PATENTEU JAN 8 FIG PAIEHTEBJAN 81974 SHEET 2 UP 2 FIG-5 SURFACE COOLER BACKGROUND OF THE INVENTION This invention relates to surface coolers. In heat transfer systems in which it is desired to reject heat from a flowing or circulating transport fluid to ram air or the like as a heat sink, it is known to pass the fluid through a flow passage in which it can achieve a heat transfer relation with the-flowing air. Heat exchangers providing such flow passage are sometimes integrated into ducting systems or the walls of enclosures and may have fins projecting into the stream of flowing air. Devices of this general class are known as surface coolers, the term deriving from the fact that air flowing over a structural surface, for example ram air over a presented surface of an aircraft, is used directly to effect the desired cooling and without recourse to heat exchangers of large frontal area.

In the prior art the efficiency of the surface coolers has been adversely affected by certain factors which it is an object of this invention to alleviate. According to one thereof, the flow passage for the heated transport fluid is exposed on only one side to conductive contact with the ram air or other flowing coolant. In another, the ram air or like flowing coolant stream is subject to aerodynamic influences, with a layer at or adjacent to the involved structural surface being stagnant or slow moving in comparison to the higher velocity, high energy air in the outer free air stream. Both factors, limited surface area and an absence of high energy air as a coolant, have an inhibiting effect on heat rejection.

SUMMARY OF THE INVENTION According to the present invention a surface cooler places the flow passage for the circulating transport fluid in a projecting spaced relation to a structural surface. Spaced apart walls defining the flow passage are both contacted by a stream of coolant flowing over the surface so that both are effective heat conductors. Fin material interposing between the structural surface and an inner wall of the flow passage establishes ties therebetween and provides secondary heat transfer surface. The opposite or outer wall of the flow passage provides primary heat transfer surface and may if desired be equipped with secondary heat transfer surface in the form of outwardly projecting fins. The coolant flow path occupied by the described fin material accordingly extends along the presented structural surface. Aerodyanmic devices at the leading end of such flow path are effective simultaneously to divert the low energy air in the boundary layer adjacent to the surface out of and away from the flow path and to encourage a flow thereto of higher energy relatively rapidly moving air from the free stream which exists outwardly of the boundary layer and is relatively unaffected by surface viscosity or friction effects.

Flow over the surface cooler is utilized additionally to facilitate escape from a vent chamber situated at the trailing end of the cooler of a third or system fluid.

An object of the invention is to provide a surface cooler reflecting concepts of novelty and improvement as discussed above.

Other objects and structural details of the invention will appear from the following description, when read in connection with the accompanying drawings, wherein:

FIG. 1 is a view in perspective of a surface cooler in accordance with the illustrated embodiment of the invention mounted to an aircraft pod providing a presenting structural surface to which the surface cooler is mounted;

FIG. 2 is a top plan view of the surface cooler of FIG.

FIG. 3 is a fragmentary view in longitudinal section, taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is a detail view in perspective, enlarged with respect to FIG. 1, showing the inlet end of the surface cooler;

FIG. 5 is a view in cross section, taken substantially along the line 5--5 of FIG. 2;

FIG. 6 is a fragmentary view in longitudinal section, taken substantially along the line 6-6 of FIG. 2; and

FIG. 7 is a view in cross section, taken substantially along the line 77 of FIG. 2.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT A structural surface swept by ram air or the like is, in the illustrated instance, represented by a pod 10 suspended from a wing or otherwise externally carried by an aircraft to dispose in the air stream. A surface cooler 11 is secured to the pod exterior, as by bolts 12, and orients in a sense fore and aft or longitudinally of the pod. In the illustrated instance, the surface cooler is a part of a heat transfer system, other components of which are within the pod 10. The cooler might, however, be connected externally of the pod and mounted thereon merely for the purpose of taking advantage of ram air flow over the pod surface.

The cooler 11 includes a lower plate 10a seating directly on the surface of pod 10. superimposing on the plate 10a is an undulating fin'strip 13. Channel members l4 and 15 dispose to either side of the fin strip 13 in a confining relation thereto. Lower portions of the channel members 14 and 15 are turned inward to seat on the plate 10a. Upper portions of the channel members I4 and 15 are similarly turned inward to provide, in conjunction with upper peak portions of the fin strip 13, a seat for a plate'member 16. In superposing spaced relation to the plate 16 is another like plate 17. The two plates are held in a spaced relation by marginal strips 18 (one shown) at the sides thereof. Within the space provided by the spaced apart plates 16 and 17 and marginal strips 18 is undulating strip fin material 19 in common contact with the plates 16 and 17. The described elements are united in an integral assembly by a brazing or like process and the assembly so formed bolted to the pod 10 as described, the bolts 12 being inserted through formed recesses 21 in the cooler assembly.

The arrangement is one to provide flow passes whereby different fluids may travel in segregated but heat transfer relation. The channel members 14 and 15, along with the plates 16 and 10a, define a first passage which extends from end to end of the cooler and is open at both ends for a free flow of air or other fluid therethrough. The plates 16 and 17, along with spacer strips 18, define a second passageway through which a second fluid may flow in segregated relation to the flow in the first described passage. The second passage is in a relatively projected relation to the pod 10, as a result of which the mentioned second fluid therein is in heat transfer relation both through the plate 16 and plate 17 with fluid flowing over the pod. The fin strip 13 and the fin strip 19 assist in establishing and maintaining a structural integrity in the cooler assembly, and, manifolds addition, provide secondary heat transfer surface whereby heat may be conducted through the plates 16 and 17 with increased facility. The passage occupied by the fin strip 13 may be described as the air flow passage since in the illustrated instance it is open to a free flow of ram air therethrough. The passage occupied by the fin strip 19 may be described as a liquid flow passage since, as will hereinafter more clearly appear, it is incorporated in a system circulating a liquid in need of cooling. Opposite ends of the liquid flow passage are closed by respective manifold 22 and 23. The former connects through end tubes 24 and 25 to a chamber 26 in a fitting 27 suitably secured to the surface of pod 10. From the chamber 26 a tube 28 projects and enters the pod to be connected into the heat transfer system therein. The manifold 23 is similarly connected by a coupling 29 to a chamber 31 in a fitting 32. A tube 33 communicates the chamber 31 with the system interiorly of the pod 10. It will be understood that a transport fluid, having absorbed heat within the internal heat transfer system is circulated outside the pod'through the presently disclosed surface cooler to have its heat rejected to ram air flowing over the pod and through the described air flow passage.

The manifolds 22 and 23 are tube-like devices metallurgically bonded in a closing relation to terminal ends of the liquid flow passage. Inwardly facing sides of the respective manifolds are slotted to communicate with the flow passage. The tubes 24 and are extensions of the ends of the manifold tube 22. They are embraced by cooler extension strips 34 and 35 from what may be considered an inlet end or inlet face of the surface cooler. The strips 34 and 35 extend approximately to the location of fitting 27 from which they are in laterally spaced relation. Insert devices 36 and 37 of inverted L-shape close the gap between the side strips 34 and 35 and the relatively centrally positioned fitting 27. The fitting 27 and the insert devices 36 and 37 complement one another in bridging the space between strip extensions 34 and 35, effectively blocking direct flow along the pod surface to the inlet of the air flow passage of the surface cooler. The fitting 27 positions relatively forwardly of the ends of extension strips 34 and 35 so that the barrier provided by the fitting and the insert devices 36 and 37 is wedge-like in configuration. Air flow along the pod surface at the location of the barrier accordingly is more readily diverted away from the entrance end of the surface cooler. It will be understood, in this latter connection, that the surface cooler is oriented on the pod so that the end with extensions 34 and 35 projects into the stream of air flowing over the pod. The open end of the air flow passage from which the side extensions 34 and 35 project accordingly is the inlet end.

The side extensions 34 and 35, together with the described barrier formed by fitting 27 and insert devices 36 and 37, define a well in advance of the inlet end of the air flow passage. Forming a floor of such well is a plate 38 which at its one end seats to the pod surface immediately in advance of the inlet end of the air flow passage. From such one end the plate 38 inclines upwardly and forwardly to overlie and to seat upon the fitting 27 and the bent over upper edges of the insert devices 36 and 37. At its outer or other end the plate 38 is bent to a substantially parallel relation to the surface of pod l0 and projects relatively to the fitting 27 and devices 36 and 37. It forms a relatively sharp edged divider 39 elevated above the pod surface by substantially the height of the fitting 27, which height approximately corresponds to the overall height of the surface cooler. The plate 38 may be brazed in place or otherwise secured, as by bolts 41.

In accordance with the characteristics of ram air flow over a presented structural surface, the air at and immediately adjacent the surface of pod 10 is relatively stagnant with low energy value. According to the instant inventive concept, the edge 39 imposes a divisional control over the flowing air. Relatively low energy air long the surface of the pod is intercepted and diverted by means of the fitting 27 and insert devices 36 and 37 to the side and away from the inlet end of the air flow passage. The air above edge 39, which has relatively higher energy content and which is therefore more valuable as a heat absorption medium, flows over the upper end of plate 38, and, in the manner indicated by arrows 42, moves down the ramp formed by inclined plate 38 and is guided thereby into the air flow passage of the surface cooler. The plate 38 and associated parts accordingly forms an aerodynamic device insuring a supply of high energy useful air for cooling while denying access to the cooler of relatively less desirable low energy air. It may be noted in this regard that the aerodynamic device is a means of achieving maximum efficiency in the air flow passage of a surface cooler while at the same time relatively elevating the liquid flow passage so that heat can be rejected from both upper and lower surfaces thereof.

Having regard to the direction of flow of air over the pod, the plate 38 and associated parts constitute an extension of what may be considered the leading end of the surface cooler. At the opposite or trailing end, the air flow passage is open for a free flow-through of air. The liquid flow passage is closed by the manifold 23 as above described. The trailing end of the surface cooler further is used in accordance with a teaching of the invention as a mounting location for means to vent another or third fluid from the heat transfer system. Thus, at the trailing end of the surface cooler a pair of plates 43 and 44 are arranged in a substantially nested relation with inner ends thereof commonly welded to the upper cooler plate 17. Inner plate 44 disposes substantially parallel to the surface plate and projects beyond manifold 23 and the outlet end of the air flow passage into overlying spaced'relation to the fitting 32. Plate 43 is in diverging relation to the plate 44 and defines therewith a chamber 45. An interconnecting wall 46 closes the chamber 45 at its wide or outer end. Inner plate 44 is relatively longer than the plate 43 and presents a ledge 47 in projecting relation to the wall 46. The wall has openings 48 therein communicating vent space 45 with an angular space 49 formed between the plates 43 and 44 beyond wall 46. Plate 43 forms an inclined ramp. Air flowing over the surface cooler and encountering ramp 43 is deflected upwardly and in leaving the outer edge of the ramp creates an area of low pressure in space 49. A negative pressure is applied through opening 48 to vent chamber 45 aiding an evacuation of fluids which may be contained therein. Outer ends of the assembly of plates 43 and 44 are supported by inserted bushings 51 and 52 mounted to the pod 10. Also interconnecting the plate assembly and pod 10 is a tubular connector 53 having a through opening 54 therein. Connector 54 is in communication at one end with the vent chamber 45 through an opening (not shown) in plate 44. It is in communication at its other end through an opening 55 with the interior of pod 10. The heat transfer system in connection with which the invention is illustratively disclosed includes a water boiler in the pod 10. Created steam from the boiler is vented through opening 55 and conducted by connector 54 to the chamber '45. There the aerodynamic means represented by the assembly of plates 43 and 44 facilitates a conducting of the vented steam to ambient surroundings. It is accomplished, moreover, in a manner to avoid access of ram air to the pod interior and by means uniquely integrated into the surface cooler construction.

We claim:

1. A surface cooler for mounting to a surface which is in the use of the cooler is swept by a current of flowing coolant, an assembly of plates superposing to define a first passage adjacent to said surface and open for free flow of the flowing coolant therethrough, said plates further defining a second passage for a transport fluid to be cooled by flow in heat transfer relation to said coolant, said assembly of plates being oriented to have a leading and a trailing end in relation to the direction of flow of the coolant over said surface, said first passage having an inlet facing into the current of flowing coolant at said leading end, and means encountered by the flowing coolant in advance of said inlet having regard to the direction of flow of the coolant capturing high energy coolant from the current of flowing coolant outwardly of said surface and supplying it to said inlet and depriving relatively slow moving low energy coolant at said surface from access to said inlet.

2. A surface cooler according to claim 1, wherein said last named means interposes a flow dividing edge in advance of said inlet in the current of flowing coolant and outwardly of said surface, said last named means inwardly of said edge blocking and diverting a low energy layer of coolant adjacent to said surface.

3. A surface cooler according to claim 2, wherein said last named means provides a downwardly inclining ramp extending longitudinally and inwardly of said flow dividing edge substantially to said inlet.

4. A surface cooler according to claim 3, wherein said assembly of plates includes side plates extending in advance of said inlet and forming with said flow dividing edge a well, said inclined ramp forming the floor of said well.

5. A surface cooler according to claim 2, wherein said second passage is in superposing relation to said first passage, characterized by manifold means closing the terminal ends of said second passage and external flow connections to said manifold means for conducting a transport fluid to and from said second passage.

6. A surface cooler according to claim 5, wherein one terminal end of said second passage is in substantially overlying parallel relation to said first passage inlet,

said external flow connections including laterally spaced apart tubes attaching at their one ends to a manifold means closing said one terminal end and extending toward said flow dividing edge and joining in a common chamber forming a part of the means blocking and diverting the low energy layer of coolant.

7. A surface cooler according to claim 1, wherein said assembly of plates is arranged to provide a coolant outlet from said first passage at said trailing end, said second passage being in superposing relation to said first passage and having terminal ends approximately coinciding with the inlet and outlet of said first passage, manifolds closing said terminal ends and external transport fluid conducting conductors connecting to said manifolds. I

8. A surface cooler according to claim 7, wherein a third fluid is brought to said surface for venting, characterized by means superposing on said assembly of plates forming a vent chamber and having ends defining leading and trailing ends in relation to the direction of flow of said flowing coolant, means for conducting said third fluid to said vent chamber, and a vent outlet from said chamber in the said trailing end of the means defining said chamber.

9. A surface cooler according to claim 8, wherein the leading end of the means defining said vent chamber inclines to a relatively elevated trailing end, the sweep of flowing coolant over the means defining said vent chamber inducing an escape of said third fluid from the outlet of said vent chamber.

10. A surface cooler according to claim 9, wherein said means defining said vent chamber disposes on said assembly of plates to project the trailing end thereof relatively to the outlet of said first passage and the approximately coinciding terminal end of said second passage.

11. A surface cooler, including means defining a presented surface swept by a flowing coolant, and an assembly of stacked plates on said surface and providing superposed first and second flow passages one of which is adjacent to said surface and another of which overlies said one passage and is in relatively elevated spaced relation to said surface, said one passage being open for a free flow therethrough of coolant sweeping over said surface, and means for closing said second flow passage for segregated flow of a heated fluid therethrough, the heated fluid in said second passage rejecting heat to flowing coolant in both an overlying and an underlying relation thereto.

12. A surface cooler according to claim 11, wherein said surface cooler orients on said surface to dispose an inlet end of said first passage into a stream of flowing coolant, characterized by flow divider means in advance of said inlet end encouraging a movement of high energy flowing coolant to said'inlet end while depriving relatively low energy coolant at and adjacent to said surface from access to said inlet. 

1. A surface cooler for mounting to a surface which is in the use of the cooler is swept by a current of flowing coolant, an assembly of plates superposing to define a first passage adjacent to said surface anD open for free flow of the flowing coolant therethrough, said plates further defining a second passage for a transport fluid to be cooled by flow in heat transfer relation to said coolant, said assembly of plates being oriented to have a leading and a trailing end in relation to the direction of flow of the coolant over said surface, said first passage having an inlet facing into the current of flowing coolant at said leading end, and means encountered by the flowing coolant in advance of said inlet having regard to the direction of flow of the coolant capturing high energy coolant from the current of flowing coolant outwardly of said surface and supplying it to said inlet and depriving relatively slow moving low energy coolant at said surface from access to said inlet.
 2. A surface cooler according to claim 1, wherein said last named means interposes a flow dividing edge in advance of said inlet in the current of flowing coolant and outwardly of said surface, said last named means inwardly of said edge blocking and diverting a low energy layer of coolant adjacent to said surface.
 3. A surface cooler according to claim 2, wherein said last named means provides a downwardly inclining ramp extending longitudinally and inwardly of said flow dividing edge substantially to said inlet.
 4. A surface cooler according to claim 3, wherein said assembly of plates includes side plates extending in advance of said inlet and forming with said flow dividing edge a well, said inclined ramp forming the floor of said well.
 5. A surface cooler according to claim 2, wherein said second passage is in superposing relation to said first passage, characterized by manifold means closing the terminal ends of said second passage and external flow connections to said manifold means for conducting a transport fluid to and from said second passage.
 6. A surface cooler according to claim 5, wherein one terminal end of said second passage is in substantially overlying parallel relation to said first passage inlet, said external flow connections including laterally spaced apart tubes attaching at their one ends to a manifold means closing said one terminal end and extending toward said flow dividing edge and joining in a common chamber forming a part of the means blocking and diverting the low energy layer of coolant.
 7. A surface cooler according to claim 1, wherein said assembly of plates is arranged to provide a coolant outlet from said first passage at said trailing end, said second passage being in superposing relation to said first passage and having terminal ends approximately coinciding with the inlet and outlet of said first passage, manifolds closing said terminal ends and external transport fluid conducting conductors connecting to said manifolds.
 8. A surface cooler according to claim 7, wherein a third fluid is brought to said surface for venting, characterized by means superposing on said assembly of plates forming a vent chamber and having ends defining leading and trailing ends in relation to the direction of flow of said flowing coolant, means for conducting said third fluid to said vent chamber, and a vent outlet from said chamber in the said trailing end of the means defining said chamber.
 9. A surface cooler according to claim 8, wherein the leading end of the means defining said vent chamber inclines to a relatively elevated trailing end, the sweep of flowing coolant over the means defining said vent chamber inducing an escape of said third fluid from the outlet of said vent chamber.
 10. A surface cooler according to claim 9, wherein said means defining said vent chamber disposes on said assembly of plates to project the trailing end thereof relatively to the outlet of said first passage and the approximately coinciding terminal end of said second passage.
 11. A surface cooler, including means defining a presented surface swept by a flowing coolant, and an assembly of stacked plates on said surface and providing superposed first and second flOw passages one of which is adjacent to said surface and another of which overlies said one passage and is in relatively elevated spaced relation to said surface, said one passage being open for a free flow therethrough of coolant sweeping over said surface, and means for closing said second flow passage for segregated flow of a heated fluid therethrough, the heated fluid in said second passage rejecting heat to flowing coolant in both an overlying and an underlying relation thereto.
 12. A surface cooler according to claim 11, wherein said surface cooler orients on said surface to dispose an inlet end of said first passage into a stream of flowing coolant, characterized by flow divider means in advance of said inlet end encouraging a movement of high energy flowing coolant to said inlet end while depriving relatively low energy coolant at and adjacent to said surface from access to said inlet. 